Data communication systems have been developed for use between vehicles and remote locations for many years. For instance, tractor/trailer combinations have been used in the trucking industry to transport cargo over the roadways while in contact with a network management facility (NMF) and/or dispatch center. However, there is a dearth of systems providing communications between a tractor and trailer which are mechanically coupled together enabling the tractor to pull the trailer. Vehicle subsystems may be powered and controlled using communication links between the tractor and trailer. These subsystems include hydraulic, pneumatic, electrical, and other subsystems connecting the tractor with the trailer using electrical conductors and pneumatic lines. Many of the connections between the tractor and trailer, (generally together considered as a vehicle and commonly referred to as a “rig,”) are standardized permitting quick-disconnect, coupling, and interchange using standardized connectors and couplers among various rig components, such as tractors, trailers and dollies (short trailers used to couple multiple trailer strings).
The dynamics of the trucking and shipping industry provide that a tractor will be connected and detached from different trailers during the course of its useful life. The standardization of connections also permits rig equipment, including the tractor and trailer to be leased, rented, loaned, sold or traded among various entities. Typically, a trailer may be hauled to a first destination, detached from a tractor and subsequently delivered to a second location by another tractor. Consequently, over its operational lifetime, a trailer may be under the control of several different concerns, including various carriers, truck brokers, trucking companies, railroads, overseas shippers, etc. Also, different operators may be at the immediate control of a tractor/trailer, etc. Various methods have been devised to track rigs and their components over the course of a delivery schedule. Untethered trailer tracking such as T2™, a well-known untethered trailer tracking system provided by QUALCOMM Inc. is used to track trailers and it may be used to track shipping containers as well. A primary purpose of un-tethered trailer tracking includes ensuring that a trailer has not been parked somewhere unused for a long period of time, e.g. years. Current systems do not readily offer an untethered communication system between tractor and trailer. Further, attempting to employ the widely used 7-pin connectors operating according to tethered protocols pursuant to standards such as Society of Automotive Engineering (SAE) J1939 (Recommended Practice for a Serial Control & Communications Vehicle Network), SAE J1708 (Serial Date Communications Between Microcomputer Systems In Heavy Duty Vehicle Applications) and SAE J1587 (Electronic Data Interchange between Microcomputer Systems in Heavy-Duty Vehicle Applications), etc. may be fraught with problems.
Communication on a data bus between a tractor and a trailer may be problematic due to the nature of the standards such as SAE J1708 and J1939. For instance, a data bus using the J1708 standard uses a differentially driven, twisted pair of wires. Further, the data bus of this system is half-duplexed such that data transmitted on the data bus is transmitted on both of the twisted pair of wires. Consequently, data transmitted on one of the twisted pair of wires is mirrored with respect to the other twisted pair of wires. Because data is transmitted on the bus on both wires, there is no separate transmit and receive line for the data bus. Consequently, systems needing to transmit data on the data bus must monitor the data bus for an idle state in order to get an opportunity to send data. Further, communication over a physical link between tractor and trailer using the 7-pin connector are subject to wear and vibration, frequently resulting in an intermittent electrical connection therebetween which is unsuitable for communications. Moreover, there are no spare electrical connections within the 7-pin connector available to provide a robust communication channel. Due to these constraints, existing tractor/trailer communication systems that utilize the 7-pin connector are very limited in capability, reliability and bandwidth.
As rigs travel between cargo terminals, delivery points, weigh stations, and the like, conventional tracking techniques can be generally classified as cumbersome and limited in effectiveness and information capacity. Frequently, tractors, trailers, and other components are identified using simple numbering systems, i.e., a serial or other number is painted on or otherwise applied to a surface of the component These numbers typically are read and recorded by human operators and the process can be a time-consuming process in an industry based on scheduling and time criticality. The likelihood of human error also increases the probability of mistakes in accounting process involving cargo since record entries may occur during conditions of darkness or obscured visibility.
Serial number or other identification numbers used on trailers or containers may fail to convey a complete cargo identity. Cargo contained within a trailer generally is not identifiable by the trailer's identification number absent a predetermined cross-reference between the number and the cargo. Although such a cross-reference typically can be supplied through a freight management database, elaborate communications systems and recording procedures may be required to ensure data integrity. Failures in the link of the accounting chain may result in erroneous component and cargo designations in a recorded cargo manifest leading to errors in shipments and misplaced components and misplaced containers.
Bar-code or magnetic-stripe identification systems have been employed to reduce the likelihood of human error involved in the numbering of cargo containers and trailers. However, since codes or magnetic stripes and the like are typically affixed to surfaces of the rig which are exposed to wind, rain, salt, and other environmental contaminants, codes and stripes may be rendered unreadable. Further, reading a bar code or magnetic stripe typically requires the close proximity of the reader and the code of stripe. This generally precludes remote reading or reading while the rig is in motion. Additionally, bar codes and magnetic stripes have a relatively limited information capacity.
Radio frequency identification (RFID) systems have been used to track trailers. However, these systems are generally passive and may not be very instrumental in the exchange of a great deal of information. For instance, a reefer, a name often applied to a truck refrigeration unit, has little suitability for use with RFID in the way of offering solutions for monitoring and controlling temperature within a reefer.
Accordingly, there is a need for a system that can result in a reliable wireless communications link between a tractor and trailer or between a tractor and storage container. However, establishing a secure and unique wireless radio frequency (RF) connection between a tractor and a trailer can be problematic in locations such as truck stops and fleet yards where multiple tractors and trailers are in relatively close proximity. Given that RF signals are not limited to line of sight and the range of these signals can be hundreds of feet, it is likely that a RF receiver on a tractor would pickup transmissions from several trailers; not just the trailer to which it is physically connected. Under these circumstances, it would be very difficult for a tractor to identify the trailer(s) with which it should establish a RF connection. The more RF enabled tractors and trailers that are present, the more problematic the situation becomes.
Applicable reference numerals have been carried forward.